(I work at the touch tank at a local aquarium. We invite guests to dip their fingers in and stroke the aquatic life as they swim past, provided they don't put in more than two fingers at a time so as not to overwhelm the animals.)

Me: "And over here we have lake sturgeon and blue gill, both native to our own Lake Michigan!"

Guest: "What are these?" *points to starfish tank*

Me: "Those are red knobbed starfish, ma'am. They're native to the Indian Ocean."

Guest: "And I can touch them?"

Me: "Absolutely! We only ask that you use two fingers at a time."

(The guest nods and proceeds to stick her thumb and forefinger into the tank, pull the starfish out, shake the water off it, and place it in her purse.)

Me: "Ma'am! Taking the marine life out of the tank is very dangerous! Please! I'm going to have to ask that you put it back!"

Guest: "But I wanted to take it home."

Me: "I'm sorry, but that's a living creature you have there. We can't just let people reach in and take out our animals!"